The need to concentrate light is relevant in many technological applications. One such application is concentrating incoming light rays from a light source onto a photodetector. Such a photodetector may be detecting the wavelength of incoming light rays, its intensity, or various other properties or signals carried by incoming light rays. Photodetectors come in various sizes with regards to the size of their active detecting surface. Their price increases significantly with an increase in their active detecting surface. A photodetector, with an active detector surface in the square centimeter range, can cost many times the amount of a similar photodetector, with an active detector surface in the square millimeter range. It is therefore cost effective to be able to concentrate incoming light onto ever smaller photodetectors. Currently, optical systems exist which can achieve the goal of concentrating incoming light rays onto small photodetectors. The optical systems currently used to concentrate incoming light rays are usually either large, bulky or not cost effective. As such, they are not well suited to be used in cases where light concentration onto small detectors is required and the physical size of such optical systems needs to be small.
U.S. Pat. No. 5,604,607 issued to Mirzaoff, and entitled “Light concentrator system” is directed to a system for collecting and concentrating electromagnetic radiation. The system includes a photosensitive medium for capturing light and a planar array located proximate to the photosensitive medium for guiding the light into the photosensitive medium. The planar array includes a plurality of concentrator elements. The concentrator elements each have a circular input and a circular output opening, and a hyperbolic cross section. Between each input and output opening is a reflective inner wall. The reflective inner wall functions to guide and concentrate radiant energy or light impinging upon an input opening through the concentrator element to an output opening towards the photosensitive medium.
U.S. Pat. No. 6,541,694 issued to Winston et al., and entitled “Nonimaging light concentrator with uniform irradiance” is directed to a nonimaging light concentrator system and nonimaging optical mixer designs that produce uniform flux for use with photovoltaic dish concentrators. The system includes a primary collector of light, such as a reflector dish, for producing highly concentrated light flux. The system further includes an optical mixer located near the focal zone of the primary collector of light. The optical mixer includes a transparent entrance aperture and a transparent exit aperture. The optical mixer further includes an internally reflective housing for substantially total internal reflection of light. An array of photovoltaic cells is located near the transparent exit aperture.
The system works as follows. Light entering the system is collected by the primary collector of light and directed towards its focal zone. At the focal zone, the light enters an optical mixer. Light inside the optical mixer is provided to the array of photovoltaic cells by substantial total internal reflection inside the optical mixer. Substantial total internal reflection provides for uniform light flux on the array of photovoltaic cells.
U.S. Pat. No. 6,302,100 issued to Vandenberg, and entitled “System for collimating and concentrating direct and diffused radiation” is directed to a system and a method for collimating light energy falling randomly from a plurality of directions onto a fixed positioned thin flat surface. The system includes a collimator for collimating incident light, a lens for concentrating light collimated by the collimator, a light funnel for further concentrating light concentrated by the lens, and a receiver. The collimated light is concentrated by an assembly of converging and diverging prismatic slabs and optical means towards the light funnel. Each prism slab's longitudinal axis is parallel to the shortest side of the collector. Each diverging prism has a first side in contact with a converging prism, and a second side in contact with another converging prism. The index of refraction of the converging prisms differs from the index of refraction of the diverging prisms.